"Anthony's childhood friend Brittany Schieber said Anthony always has been "a good-hearted person and someone who liked to have fun."
The two attended Colonial High School but drifted apart until recently, when they rekindled their friendship. Caylee and Schieber's son are close to the same age.
Schieber said she thought it was a joke when Anthony sent her a July 15 text message, telling her that she had not seen Caylee in 31 days."
http://www.orlandosentinel.com/news/local/orl-casey0908aug09,0,1517604.story
And Amy also knew as per her myspace page where she talks about Casey stealing from her and then about Caylee being missing.